WHISTLER-TRIGGERED VLF EMISSIONS RECORDED AT JAMMU DURING DAY TIME

Whistler-triggered VLF emissions recorded at low latitude station Jammu (Geomagnetic latitude = 220 26/ N; L = 1.17) during day time period on 19th February 1999 at 14:35 hrs. IST. The recorded data have been analyzed. Based on whistler-triggered VLF emissions spectrum, the VLF waves propagate along the path with L – values lying between L = 4.4 and 4.38. During the observation period, magnetic activity was very high. Mostly these types of emissions recorded at mid latitudes. These whistler-triggered emission waves propagate along the geomagnetic field lines either in a ducted mode or in a pro-longitudinal mode. Relative amplitude of whistlers waves is almost equal to relative amplitude of triggered emissions. The proposed generation mechanism explains through the dynamic spectra of the whistler-triggered emissions.

Change in the amplitude of strong discontinuity wave propagating in a rod made of Murnaghan material

The paper presents calculations of the change in amplitude of strong discontinuity wave propagating in a thin rod made of hyperelastic Murnaghan material. Two functions were assumed for the calculations, describing the change of the cross-section of the rod with the constant scaling parameter?for both decreasing cross-sections of the analysed steel rods. A numerical analysis was performed based on analytical solutions. The analytical form of solution for both rods with decreasing cross-sections allowed for preparation of contour maps for the propagating wave of strong discontinuity. Furthermore, the changes in the relative amplitude of the propagating shock wave in a thin rod were determined for two rods analysed in the study, for which the differences in the values of the relative amplitude in the final cross-section were found.

Multichannel adaptive deconvolution based on streaming prediction-error filter

Deconvolution mainly improves the resolution of seismic data by compressing seismic wavelets, which is of great significance in high-resolution processing of seismic data. Prediction-error filtering/least-square inverse filtering is widely used in seismic deconvolution and usually assumes that seismic data is stationary. Affected by factors such as earth filtering, actual seismic wavelets are time- and space-varying. Adaptive prediction-error filters are designed to effectively characterise the nonstationarity of seismic data by using iterative methods, however, it leads to problems such as slow calculation speed and high memory cost when dealing with large-scale data. We have proposed an adaptive deconvolution method based on a streaming prediction-error filter. Instead of using slow iterations, mathematical underdetermined problems with the new local smoothness constraints are analytically solved to predict time-varying seismic wavelets. To avoid the discontinuity of deconvolution results along the space axis, both time and space constraints are used to implement multichannel adaptive deconvolution. Meanwhile, we define the parameter of the time-varying prediction step that keeps the relative amplitude relationship among different reflections. The new deconvolution improves the resolution along the time direction while reducing the computational costs by a streaming computation, which is suitable for handling nonstationary large-scale data. Synthetic model and field data tests show that the proposed method can effectively improve the resolution of nonstationary seismic data, while maintaining the lateral continuity of seismic events. Furthermore, the relative amplitude relationship of different reflections is reasonably preserved.

Surface gravity wave interaction with a submerged composite wavy porous plate attached to a vertical wall

The hydrodynamic performance of composite wavy submerged porous plate attached to a wall is investigated using numerical method MDBEM (Multi-domain boundary element method) in the linearized water wave theory in which wave past the porous barriers are modelled using Darcy law. Effect of the presence of wall on the hydrodynamic parameters like reflection coefficient, dimensionless wave height, wave force and moment acting on the composite wavy porous structure and horizontal force on the vertical rigid wall is analyzed for various physical parameters like the number of ripple wavelength, structural porosity, submergence depth and relative amplitude of composite wavy porous plate. The study demonstrates that the efficiency of hydrodynamic characteristics of the composite wavy porous plate attached to the wall is better compared to a horizontal porous plate attached to the wall of the same applicability conditions (around 27% reduction in wave reflection). Moreover, optimum performance of this kind of breakwater system is increased by considering the lower submergence, higher relative ripple amplitude, appropriate relative amplitude and suitable moderate porosity of the structure in the range of wave number 1 < k0h < 5. Dimensionless wave height, horizontal load on the impermeable wall are reduced to zero, whilst substantial minimization of vertical load on the structure with suitable consideration of the other influencing parameters of porosity Gp = 0.3, relative amplitude Ds/h = 0.1, relative ripple wavelength m > 3 and submergence depth h1/h = 0.3. The present structural arrangement will be useful for attenuating wave effects on the sea wall.

Severity Estimation of Defects on Interpretation of Eddy-Current Defectograms

To ensure traffic safety of railway transport, non-destructive tests of rails are regularly carried out by using various approaches and methods, including eddy-current flaw detection methods. An automatic analysis of large data sets (defectograms) that come from the corresponding equipment is an actual problem. The analysis means a process of determining the presence of defective sections along with identifying structural elements of railway tracks in defectograms. At the same time, severity estimation of defined defects is also of great interest. This article continues the cycle of works devoted to the problem of automatic recognition of images of defects and rail structural elements in eddy-current defectograms. In the process of forming these images, only useful signals are taken into account, the threshold levels of amplitudes of which are determined automatically from eddy-current data. The article is devoted to the issue of constructing severity estimation of found defects with various lengths. The construction of the severity estimation is based on a concept of the generalized relative amplitude of useful signals. A relative amplitude is a ratio of an actual signal amplitude to a corresponding threshold level of useful signals. The generalized relative amplitude is calculated by using the entropy of the half-normal distribution, which is assumed to be a model for a probability distribution of an appearance of certain relative amplitudes in an evaluated defect. Tuning up the formula for calculating severity estimation of a defect is carried out on the basis of eddy-current records of structural elements. As a reference of the most dangerous defect, the bolted rail joint is considered. It models a fracture of a rail. A reference weak defect is a flash butt weld, a defectogram of which contains signals with low amplitude values. The proposed approach to severity estimation of defects is shown by examples.

768 The Relationship Between Circadian Rhythm and Autism Spectrum Disorder Traits and Executive Function Across the Life Span

Introduction Children and adults with autism spectrum disorder (ASD) often have sleep, circadian, and executive function impairments, which can affect daytime quality. Yet, the relationship between sleep or circadian traits and ASD traits is still unknown. Thus, we aimed to determine if sleep and circadian traits were associated with ASD traits, including executive function. Methods We studied data from participants with and without ASD enrolled in the family-based study Autism Spectrum Program of Excellence (ASPE), University of Pennsylvania. We used GGIR to analyze actigraphy-derived sleep and circadian traits from 250 participants (219 adults ages 18–87 years, mean 44.2 ± 17.3 years; 31 children ages 4–17 years, mean 11.3 ± 3.9 years). These traits were compared to ASD traits (social impairment and restricted/repetitive behavior via Social Responsiveness Scale, Second Edition) and executive function (Behavior Rating Inventory of Executive Function) using linear multivariate regression models adjusted for age, age2, and sex via Sequential Oligogenic Linkage Analysis Routines. Results In adults, earlier start time of the 10 hours of highest activity in a 24-hour day (M10 start time; p = 0.02), decreased robustness of the rest/activity rhythm (relative amplitude; p = 0.03), and increased intradaily variability of rest/activity rhythm (p = 0.04) were associated with more social impairment. In children, earlier M10 start time (p = 0.02) and decreased relative amplitude (p = 0.03) were associated with more social impairment. In adults, higher average 5-hour period of lowest activity in a 24-hour day (L5 average; p = 0.03), lower average 10-hour period of highest activity in a 24-hour day (M10 average; p = 0.005), earlier M10 start time (p = 0.02), decreased relative amplitude (p = <0.001), increased intradaily variability (p = <0.001) and decreased sleep efficiency (p = 0.04) were associated with increased executive function impairment. In children, earlier M10 start time (p = 0.006) and intradailty variability (p = 0.008) were associated with increased executive function impairment. Conclusion Circadian traits are significantly associated with ASD traits, including executive function, suggesting the importance of sleep-wake rhythm dysfunction in ASD. Support (if any) Anonymous donor; NIH T32HL07713; University of Pennsylvania’s Institute for Translational Medicine and Therapeutics

Associations of Actigraphic Sleep and Circadian Rest/Activity Rhythms with Cognition in the Early Phase of Alzheimer’s Disease

Study Objectives To compare sleep and circadian rest/activity rhythms (RARs), quantified by standard and novel actigraphic metrics, between controls and participants with mild cognitive impairment (MCI), and to examine the cross-sectional relationships between these measures and cognition. Methods Actigraphy data were collected in 179 older individuals (mean age=72.6 years) with normal cognition (n=153) and MCI (n=26). Sleep parameters (e.g., sleep efficiency), and standard non-parametric RARs (e.g., interdaily stability) were generated. Functional principal component analysis (fPCA) was used to generate three novel RAR metrics (fPC1, fPC2, fPC3). Cognitive composite scores reflecting episodic memory and executive function were derived using factor analysis. Regression models compared sleep and RAR parameters between diagnostic groups and their association with cognitive performance. Results Compared to controls, the MCI group exhibited lower levels of the standard RAR parameter: relative amplitude, and fPC3—a novel RAR whereby lower scores reflected a lower rhythm peak, as well as greater nighttime activity and less activity in the morning. Across groups, several standard RAR parameters (e.g., interdaily stability) and fPC3 were associated with better episodic memory and executive function performance. Additionally, several standard RAR measures (e.g., relative amplitude) and the novel RAR measure fPC1 (reflecting the total volume of activity and rhythm strength) were associated with better executive function performance. Conclusions Individuals with MCI have altered circadian RARs compared to controls, including the novel RAR metric fPC3, reflecting greater nighttime activity and less activity in the morning compared to mean values. Additionally, these measures are significantly associated with cognitive performance.

Diurnal Rhythm Robustness in Individuals With PTSD and Insomnia and The Association With Sleep

Posttraumatic stress disorder (PTSD) and insomnia are characterized by sleep disturbances and daytime functional impairments. Actigraphy metrics can quantify diurnal rhythms via interdaily stability, intradaily variability, relative amplitude, and sleep regularity. Here, we (a) compared diurnal rhythms in PTSD, insomnia, and healthy control samples using linear mixed modeling; (b) compared inter-individual variability of diurnal rhythms between groups using variance ratio tests; and (c) examined correlations between diurnal rhythms and sleep measures within the clinical samples. Participants ( N = 98) wore wrist-activity monitors for one week and completed the Insomnia Severity Index and Pittsburgh Sleep Quality Index. Both clinical samples displayed significantly lower interdaily stability, relative amplitude, and sleep regularity compared with controls. Individuals with PTSD and insomnia did not differ on mean diurnal rhythm metrics. Both clinical samples showed more inter-individual variability in relative amplitude compared with controls, and the individuals with PTSD were distinguished from those with insomnia by greater inter-individual variability in interdaily stability and relative amplitude. Relative amplitude in the clinical samples was positively correlated with objective sleep efficiency and total sleep time. This is the first study to compare individuals with PTSD and insomnia on measures of diurnal rhythms, revealing those with PTSD and insomnia to have less robust and more variable diurnal rhythms compared with controls. Individuals with PTSD differed from those with insomnia in inter-individual variability of diurnal rest-activity stability and amplitude, highlighting this population as particularly heterogenous. Diurnal rhythm robustness might be considered an intervention target in insomnia and PTSD populations.

Genome-wide correlation analysis to identify amplitude regulators of circadian transcriptome output

Cell-autonomous circadian system, consisting of core clock genes, generates near 24-h rhythms and regulates the downstream rhythmic gene expression. While it has become clear that the percentage of rhythmic genes varies among mouse tissues, it remains unclear how this variation can be generated, particularly when the clock machinery is nearly identical in all tissues. In this study, we sought to characterize circadian transcriptome datasets that are publicly available and identify the critical component(s) involved in creating this variation. We found that the relative amplitude of 13 genes and the average level of 197 genes correlated with the percentage of cycling genes. Of those, the correlation of Rorc in both relative amplitude and the average level was one of the strongest. In addition, the level of Per2AS, a novel non-coding transcript that is expressed at the Period 2 locus, was also linearly correlated, although with a much lesser degree compared to Rorc. Overall, our study provides insight into how the variation in the percentage of clock-controlled genes can be generated in mouse tissues and suggests that Rorc and potentially Per2AS are involved in regulating the amplitude of circadian transcriptome output.